| AC | Alternating current, or current flow that switches back and forth. This is the type of power that comes in on the line to your house and is available at a common outlet. |
| API | Application programming interface; it's all layers, really—programs talking to programs talking to programs, and so on and so on and so on…. That or it is a simple cake. |
| Back EMF | EMF means electromotive force, which is used to describe the voltage generated when you spin the armature of a DC permanent magnet (PM) motor. The term is also used to describe the voltage generated at the connections of an inductor when you stop pushing current through it and the magnetic field collapses. Since they are both voltages caused by a changing magnetic field, it makes some sense. |
| Bias | A widely used term in electronics. Bias can refer to the voltage applied to a circuit. For example, a DC bias or offset is a way of shifting an AC signal from one level to another, such as biasing a circuit or component to a level where you get a predictable behavior. You can bias the input of a transistor, for instance. |
| BS | Come on, everyone knows what BS means! |
| BTW | By the way; the only reason I need to define this is for old farts like me who were raised without a cell phone and text messaging! |
| Bulk cap | A large-value capacitor, usually 1 μf or bigger, commonly 100 μf to 0.1 f. Usually an electrolytic cap, not typically good at fast frequencies but has plenty of current capability. |
| Cap | Capacitor, a plate-like unit with a space of something that won't conduct electricity between the plates. A cap has the capacity to store energy in the form of an electric field. |
| Chip | Slang for IC. You will often hear engineers refer to ICs as chips. It doesn't always mean they are hungry for lunch! |
| Current | Describes the movement of electrons, commonly thought of as a flow. In the water analogy, this is the amount of water moving. Amp is the basic unit of current in an electrical circuit. Common symbols are I and, less often, A. |
| DC | Direct current, or current flow that goes in only one direction. This is the type of power that comes from a battery. It is the type of power computers and most electronics use internally in their circuits. |
| DCPM | Short for direct current permanent magnet motor. These little guys are everywhere. |
| DMM | Damn meter won't measure; a cuss phrase often let loose when an engineer has yet to discover that the fuse is blown in his digital multimeter. Usually precedes stalking off to the lab to find a screwdriver since you have to tear the whole meter apart just to replace a fuse. |
| Drain | Usually this is the connection on a device that “drains” current from whatever it is hooked up to. |
| Drive | To drive a part means to apply current and voltage to make the part do what you want. You drive a load. If asked what a ____ is capable of driving, it means how much can it sink and source. |
| Duty cycle | A percentage of on-time versus off-time—how much time the component is on duty, so to speak. If a motor has a 30% duty cycle, that means it is being used 30% of the time; the other 70% of the time it is off. |
| EPROM | Way back when our PROMs only had one E, you had to erase them with UV light. Oh yeah, it means erasable programmable read-only memory. Does that mean EPROMs technically were “easy to sunburn”? |
| EMI | Electromagnetic interference is anything and everything that interferes with an electric or electronic circuit. It is sometimes attributed to supernatural causes by superstitious engineers. |
| EULA | Everyone is Unable to take Legal Action if this product destroys your data. If you have never agreed to a EULA and you own this book, well, wow. I am left at a complete loss trying to come up with a quirky remark. |
| FAE | Fairly Astute Engineer. Most FAEs I have met are pretty smart, or I am just jealous that they got the easy job? I'm not really sure. Oh yeah, it also means field application engineer. |
| Flame mail | An email message that is sent with the intent to harm, not actually communicate. |
| Flux | Flux, or resin, is an acid either applied separately or in the core of the solder. When heated, it cleans the joint to help the solder stick better. |
| Forward bias | Refers to the biasing of a diode; when forward-biased, a diode passes current. |
| Freewheel diode | A reverse-biased diode hooked up in parallel with a motor. It is there to capture the inductive current generated as the magnetic field collapses. |
| Gate | This means a couple of slightly different things: a logic part, NAND gate, NOR gate, etc., or a connection on an FET that controls the current flow from drain to source. Note that it isn't all that different from how a “gate” can keep or let out sheep in a corral—that is if you can compare sheep to electrons. Now there is an analogy that would be fun to explore. |
| Gnd, Vss | The voltage reference point. Usually you connect one lead of a measuring instrument to this point. It is also the place all the current returns to (conventional flow again) that comes from Vcc. In electron flow terms, it is the point that spews forth electrons. |
| Grok | Martian term in the book Stranger in a Strange Land by Robert Heinlein. It means to understand completely, in the most intimate way. |
| Ground | Often used interchangeably with circuit gnd, ground should be thought of differently. Ground is the dirt under your feet into which you drive a big stake and hook it up to the exposed metal (and sometimes the gnd) of your circuit. This is done for safety reasons. |
| HW | Abbreviation for hardware. |
| IC | Integrated circuit, a device that is made up of a combination of diodes and transistors and other basic parts etched into a silicon base; it's used to make things as simple as switches and as complex as the Intel Pen-way-cooler-than-the-last-chip-tium in your PC. |
| Impedance | Seen as a Z in many equations. Think of this as resistance that takes frequency into account. Used in conjunction with inductors and capacitors. |
| Inductor | A coil of wire at its most fundamental; it can store energy in the form of a magnetic field. When a magnetic field changes, it induces current to flow in a wire. The coils concentrate the magnetic field. |
| Iron | Soldering iron used to create solder junctions. No, you don't want to iron your shirt with this device! |
| ISA | Intuitive signal analysis—the first acronym of my own invention. I figure if I ever want to be a famous engineering writer, I'd better have one or two acronyms to my name. |
| JAVA | Nice cup of Joe, that or some programming language cool enough to be talked about at the coffeeshop. |
| Junction | The place at which two semiconductors come together. |
| Ladder logic | A type of programming method or language; its name comes from the ladder-like appearance of the diagram used to describe the program. |
| Lead | A pin on an electronic part, such as an IC, used to connect the part to the PCB. |
| Leaky cap | An imperfect capacitor that allows some amount of DC current to pass. |
| Linear | A term often used in conjunction with supply or control. A linear control is one that controls voltage to a part continuously. The part controlling this will dissipate energy based on the voltage across it and the current through it. It is typically an inefficient way to drive a load, since the power that is not used is turned into heat. |
| Load | Something that takes power, needing both current and voltage, to drive. A resistor that returns current from Vcc to gnd is a load. |
| Magic smoke | The stuff inside all ICs that makes them work. You don't want to let it out! |
| MAMA | Management always chasing the market around. My own personal acronym. If you want to be successful in the world of engineering, you have to invent an acronym or two. Chalk up another one for me! |
| MCU | Microcontroller, which is like a CPU but less powerful, with more stuff built in. |
| NO, NC | Pronounced nnnn ohhh and nnn seee. A cryptic abbreviation for the typical state of a switch or relay connection. See, even in engineering, NO doesn't always mean no. |
| OPM | Other people's money; it's always more fun to play around with other people's money than with your own. |
| OS | Operating system. |
| OTP | One-time programmable. Before Flash became the memory of choice in embedded micros, one chance was all you got. There are still a few OTPs out there, but you are probably in some really high volumes if you're using these. It's likely you are into masked parts as well. |
| Pad | Not the place where you hang out! It's the point on a PCB of bare copper where the leads of a part are connected by solder to a trace. |
| PCB or PWB | Printed circuit board or printed wiring board. A composite material, usually stiff like a board, on which a circuit is laid out, creating connections between components. |
| PDA | Pretty dumb assistant. I'd trade my PDA for a real live flesh-and-blood assistant any day! |
| PLD | Programmable logic device. Take a whole bunch of memory cells, a slew of logic gates, a bunch of multiplexers, and a way to configure it all, and then cram everything into a single IC. At the end of all this, you get a product that can do a whole bunch of state machine and logic stuff. You can even make MCUs out of them, as in sister products such as the FPGA. |
| PM | Permanent magnet. |
| Pointy hair | We have Scott Adams to thank for this unique term, which we can now use to refer to our bosses. |
| Power | The combination of voltage and current. This is what turns the lights on in your house. The unit for power is the watt. The common symbol is W. Watts can be converted to horsepower (HP); it takes 746'W to make 1'HP. Another symbol you might see that is loosely related to watts is VA, or volt amps. The symbol is generally used in power supply systems to refer to AC power; it is equivalent to watts only when the current and voltage match phases. |
| Power component | A term commonly used to refer to parts that handle a large amount of current or high voltage. Of course, the words large and high are relative. It means a current large enough so that you need to worry about things like heat and voltage, and high enough so that it will do more than tickle a little if you touch it. |
| Power device | A common term used to refer to semiconductor devices, such as FETs and transistors, that take a small low-power input signal and amplify it into a high-power signal. Power devices usually need to be meticulously handled in your design to avoid overheating. They often have a surface that is designed to be coupled to a heat sink to manage the power dissipated as they operate. |
| Pull-up | A resistor from an input line to Vcc. In the absence of any other current flow, it “pulls” the voltage at that node to Vcc. |
| Pull-down | A resistor from an input line to gnd. In the absence of any other current flow, it “pulls” the voltage at that node to gnd. |
| PWM | Pulse width modulation. A digital method of controlling a voltage level. The percentage of time-on versus time-off determines the amount of power applied to the load. |
| R | Pronounced arrrrr, as in “What is the arrr of that puppy?”; it means resistance—something that resists the flow of current proportional to the voltage. It is the R in Ohm's Law. |
| Rail | The voltage limit to which an output can swing. The top rail is the highest positive voltage it can get to, and the bottom rail is the lowest voltage it can get to. This is not necessarily the same as the power supply. Some devices cannot get the output to reach Vcc or gnd in the circuit. When the output is at these limits, it is common to say it is “railed.” |
| RC | Radio control. A fun hobby that you can dump a lot of money into. Also means resistor/capacitor circuit. |
| Rectify | Rectify or rectification is the process of turning AC power into DC power. |
| Reverse bias | A specific case of biasing, usually referring to a diode. When a diode (or diode-type junction in a component) is reverse-biased, the diode blocks current flow. |
| RSP | Really smart person. I love to talk to really smart people; that is, when I can understand what they are saying! |
| Sink | No, not the kitchen sink, but it does act a little like a drain; generally used in a phrase such as “How much can that sink?” It means how much current is capable of going into ground through that part. |
| SNL | Saturday Night Live. There is always something good on SNL. |
| Solder | A material used to make electrical connections. It is heated to create that connection. |
| Source | A term often used in a phrase such as “How much can that source?” It means how much current is capable of coming out of that part. Both sink and source assume conventional current flow terminology from positive to negative. |
| Sparky | A widely used slang term to refer to an electrical engineer, at least in the world of Darren. (We tried to assign the term “wrench” to the MEs, but it just doesn't have the same ring to it.) |
| State machine | A computing device that looks at the state of the inputs to determine the output. More complex forms of this device feedback outputs to the input and/or maintain memory of certain inputs. |
| SW | Abbreviation for software. |
| Switcher | A cousin to the linear control or supply. The switching control is digital in nature. Somewhere in the system is a switch that turns on and off cycling power to the load. The amount of time-on versus time-off is called the duty cycle; it is defined as a percentage. Often there is an inductive or capacitive component in or attached to the load that filters the frequency of the switching device to smooth out the voltage or current to the load. |
| Switch mode | The digital control of a device such as a transistor or FET, for example. The part is either turned all the way on or off, like a switch—hence, switch mode control. Using a device like this in applications, such as a switching power supply, helps make them more efficient because less heat is created when a part is not in the linear region of operation. |
| Threshold | In electronics, a voltage level that, when crossed, changes the output state of a logic circuit from 1 to 0, or vice versa. |
| Tinning | Refers to applying solder to the tip of an iron or to a wire to help heat transfer. |
| Trace | The little green lines you see on a PCB. They are made of copper and are the wires that connect the parts. Trace can also refer to a method of troubleshooting software. |
| Vcc, Vdd | The voltage source in the circuit. In conventional flow terms, it is the place all the positive holes come from. In electron flow terms, it is the place all the electrons try to get to. |
| Via | A hole in a PCB that on some PCBs is coated with copper. It is used for two reasons: either to create a connection between a top trace and a bottom trace or to create a hole in which a part lead can be inserted and soldered to the PCB. |
| Voltage | The potential of the available electrons. Using the water analogy, this is the pressure the current is under to move. The unit for voltage is the volt. Common symbols are V and E. |
| Voltage drop | The voltage measured across a component, such as a resistor. Not a “drop” in a bucket or anything like that; it's simply techno-speak indicating the difference in voltage as measured from one side of a component to another. (Since what you measure is relative, you can always switch the meter leads to make it look like a “drop” in voltage.) If a voltage drop increases or decreases, this means the absolute value or magnitude of the change in voltage across the component is increasing or decreasing. |
| Zebra | Not used anywhere in the book, but I just had to have a ‘Z’ term in my glossary to be complete! Wait a minute… I should have used Zener, now there is a sparky word that is fun to say, try it now, say Zener three times real fast, I bet it makes you smile! |